The present invention relates to a group supervisory system of elevator cars.
One of the effective and useful systems to control a bank of elevator cars is the system wherein the choice of a car to serve one of the hall calls with respective functions generated at the respective floors of an office building is decided by taking note of the traffic condition and car travelling condition in the whole building.
This system is called the assigning system which is most commonly employed at present in the group supervisory system of elevator cars and can provide considerably improved service, compared to the conventional elevator control system, i.e. the so called one-round operating system, in which the elevator cars are operated with proper intervals regardless of generation of the hall calls.
Diverse propositions have been made for the assigning system, i.e. the system to select the car to serve the hall call. One such of the systems which are considered to be most effective ones is that the time (waiting time) from generation of a half call to arrival of an elevator car at the floor giving the floor call is directly estimated and the car is assigned in a manner that the sum of the estimated times over all the floors is minimized.
Any of the elevator control systems in which the waiting time is directly estimated and the estimated time is used as an evaluation value, including the just-mentioned system, has a disadvantage; the fretful sensation of human beings for waiting is assumed to be substantially proportional to the physical time of waiting. In other words, anyone feels a longer waiting time than the physical time as the waiting time is longer. From the view point of fact, a curve y showing the evaluation value as a non-linear function of the waiting time is longer (e.g. v=(t/10).sup.2), must be fit for the waiting time sensation of human being beings rather than assuming that the evaluation value v is proportional to the waiting time t(e.g. v=t/10) as shown in line x in FIG. 1. However, if the evaluation value for the waiting time longer than a predetermined time is treated as that for a long waiting time and a priority of the car service is given to the floor with such an evaluation value, a great measure of inaccuracy is introduced into the elevator control.
In other words, the conventional elevator control system was such that, as indicated by a line x' in FIG. 2, the chance in the evaluation value v' is the same for each unit waiting time regardless of the length of the waiting time t'. When the sensation of the human being is taken into consideration, however, the change in the evaluation value v' for each unit waiting time must be larger as the waiting time t' is longer, as indicated by a line y'.